Studies on Labrid Fish Confirm Operational Gravity Well Model for Adaptation
- Brian Miller
In my previous article, I described how studies on insect wings validate engineering models for adaptation. Now I will further demonstrate the predictive power of the operational gravity well model (OGWM) from studies on labrid fishes (wrasses).
Predictions of the Model
OGWM presupposes that an organism’s design plan demonstrates a coherent logic based on engineering principles. That plan is founded on an underlying architecture or blueprint that is immutable. Any mutational or environmental perturbation that alters the core framework will debilitate the organism.
The design plan will also include parameters that can vary to help a population to adapt to changing circumstances. For instance, a finch’s beak will always maintain the same basic structure, but predetermined variables associated with that structure can hold a bounded range of values. Examples include a beak’s width, length, thickness, sharpness, and material content.
The model also predicts that anytime a new design plan is identified, it will appear in the fossil record suddenly without a series of ancestors leading back to a common ancestor shared with other species whose body plans are based upon different architectures. During an organism’s tenure on earth, only the adjustable variables can change; the underlying design logic will always remain intact. Studies of labrid fishes (wrasses) confirm all these predictions.
Four-Bar Linkages
The jaws of wrasses conform to a clearly identifiable design logic. Westneat et al. in a 2005 study identified the underling design of the jaws as the four-bar linkage motif commonly implemented in human engineering:
In addition to the jaw lever, a linkage system in the jaws (figure 3i–k) transmits lower jaw rotation to the maxilla and the sliding upper jaw, the premaxilla (Westneat 1994). This is a four-bar linkage, an engineering design that is used in bolt cutters, typewriter keys, heavy construction equipment and many other human-engineered machines that precisely transfer force or motion.
The investigators catalogued multiple versions of the four-bar linkage in different labrid species. Each version is based on a different design architecture that is subject to tight “physical constraints.” Any fundamental change to any of the underlying designs must correspond to another “engineering system” replacing the original:
These taxa with additional joints and links in the transmission system represent engineering breakthroughs in cranial design…
Skull mechanisms such as levers and linkages are subject to physical constraints (Westneat 2003), which may only be broken when a fundamentally new engineering system for feeding arises.
The constraints do not solely correspond to the architecture of the bones and their connective tissues. Westneat’s 2003 article demonstrated how each version of the linkage system also requires tailored jaw muscles:
Adductor jaw muscles with different mechanical designs must have different contractile properties and/or different muscle activity patterns to coordinate jaw closing.
Taking the investigators’ statements at face value, they seem to acknowledge that one feeding system cannot fundamentally change into another gradually. Instead, any transformation requires multiple coordinated modifications at once. The extent to which the authors recognize the implications of their conclusions is difficult to say.
Fossil Record and Common Ancestry
In addition, species with new jaw designs always appear in the fossil record suddenly (aka punctuated appearances). And the same design often occurs multiple times independently (aka convergence). Westneat et al. commented:
The macroevolutionary history of labrid fishes on global reefs has involved species divergence in skull structure within a range of mechanically feasible forms, creating an unparalleled higher-level pattern of convergence that is occasionally punctuated by major transitions in engineering design.
Not only do these observations perfectly match OGWM’s predictions, but they demonstrate how the assumption of common ancestry directly conflicts with the fossil record and taxonomy. The distribution of the different jaw designs does not fit into a consistent evolutionary tree. Nor could the different jaws have gradually evolved even once, let alone multiple times. Instead, the same jaw design was independently implemented in different species to achieve the same goals, such as eating similar types of food. The distribution pattern does not conform to the predictions of an undirected evolutionary process, but it demonstrates the foresight and creative power of an intelligent designer.
